In January, the Architectural Billings Index (ABI) sunk to 33.3, the lowest level in its 13-year history. The score has fallen below 50 for 12 straight months; a score above 50 indicates an increase in billings, and below 50, a decrease.

One of the profession’s leading economic indicators, the index is compiled by the American Institute of Architects (AIA) and is based on surveys sent largely to commercial firms. It reflects a nine- to 12-month lag time between architectural billings and construction spending.

The inquiries score for January was 43.5. In terms of project sectors, the score for multi-family residential was 29.5 and for commercial/industrial, 33.8. The institutional score slipped to 37.1, from 38.3 in December.

Kermit Baker, the AIA’s chief economist, is hopeful that the $787 billion federal economic stimulus package will reinvigorate the industry. “Now that the stimulus bill has passed and includes funding for construction projects, as well as for municipalities to raise bonds, business conditions could improve,” he says. “That said, until we can get a clearer sense of credit lines being made available by banks, it will be hard to gauge when a lot of projects that have been put on hold can get back online.”

Read more economic news in our Recession and Recovery special section.